I. Field of the Invention:
This invention relates generally to two-dimensional object recognition and, more particularly, to a system for two-dimensional object recognition using chain codes, histogram normalization and trellis algorithms.
II. Discussion of the Prior Art:
Object recognition of two-dimensional objects is useful in a variety of applications including manufacturing and military applications. Two-dimensional object recognition can be used, for example, in connection with robotics on an assembly line, or in association with a military target recognition system. Desirable features of such a recognition system include the ability to recognize two-dimensional objects independent of rotation and size variations of two-dimensional objects with a minimum of complexity and a high degree of robustness. By minimizing the complexity of the system, fast, real-time, object recognition can be achieved. If such a system is also highly insensitive to noise, the system is said to be robust.
Known object recognition systems such as the "2D invariant moments" theory provide an algebraic approach to object recognition. Such systems yield variables or values which are numbers related to the shape of the object. One limitation of the 2D invariant moment approach is that changes in size or rotation will change the values obtained because such systems are very sensitive to noise. The 2D invariant moment system is complex and slow. It may become extremely slow and even more complex when scaling and rotational factors are present in the unknown object being classified or identified.